1. Paraffin sections of dog and rabbit pancreas were silver-impregnated with modified DAVENPORT method and ca. 5% of the islet cells were blackened.
2. By bleaching and restaining (MASSON-GOLDNER) the silver-impregnated sections, it was revealed that the argyrophil cells are identical with D-cells tinged in light green. This result corresponds to that obtained recently by the same author in the holocephalian fish but is discordant with the previous views that argyrophil cells are identical with A-cells (FERNER and others) or with a group of them (VOLK, HELLMAN and their coworkers).
3. The high specificity of D-cells in the argyrophil reaction confirmed in this study implies the utility of the silver impregnation method for the study of these cells.